KR100931509B1 - Nitride semiconductor light emitting device and manufacturing method - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitride semiconductor light emitting device and a method of manufacturing the same, and more particularly, to a nitride semiconductor light emitting device and a method of manufacturing the same, which provide a current spreading layer to a semiconductor light emitting device to improve luminous efficiency.

A nitride semiconductor light emitting device according to the present invention, the first n-GaN layer; A current spreading layer formed on the first n-GaN layer; A second n-GaN layer formed on the current spreading layer; An active layer on the second n-GaN layer; It includes a p-GaN layer formed on the active layer.

In addition, the method for manufacturing a nitride semiconductor light emitting device according to the present invention comprises the steps of: forming a first n-GaN layer on a substrate; Forming a current spreading layer on the first n-GaN layer; Forming a second n-GaN layer on the current spreading layer; Forming an active layer on the second n-GaN layer; Forming a p-GaN layer on the active layer.

Nitride Semiconductor Light Emitting Device

Description

Nitride semiconductor LED and fabrication method

1 is a longitudinal cross-sectional view showing a laminated structure of a conventional nitride semiconductor light emitting device.

2 is a longitudinal sectional view showing a laminated structure of a nitride semiconductor light emitting device according to the first embodiment of the present invention;

3 is a longitudinal sectional view showing a laminated structure of a nitride semiconductor light emitting device according to a second embodiment of the present invention;

<Explanation of symbols for main parts of drawing>

10, 100: nitride semiconductor light emitting device 12, 102: substrate

14, 104: buffer layer 106: undoped GaN layer

108: first n-GaN layer 110a, 110b: current spreading layer

112: second n-GaN layer 124: p-GaN layer

18, 120: active layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitride semiconductor light emitting device and a method of manufacturing the same, and more particularly, to a nitride semiconductor light emitting device having a light emitting efficiency improved by providing a current spreading layer in a semiconductor light emitting device.

In general, the nitride semiconductor light emitting device has a light emitting area covering the ultraviolet, blue and green areas. Particularly, GaN-based nitride semiconductor light emitting devices are optical devices of blue / green LEDs and high-speed switching, high-output devices such as HEFETs (Metal Semiconductor Field Effect Transistors) and HEMTs (Heterojunction Field-Effect Transistors). It is applied to.

As shown in FIG. 1, the conventional GaN-based nitride semiconductor light emitting device 10 mainly forms the buffer layer 14 at a high temperature on a sapphire substrate 12 or a SiC substrate and has an n-GaN layer 16 thereon. It is formed of a multi-quantum well structure and comprises an active layer 18 and a p-GaN layer 20 for emitting light.

In this case, an electrode layer (not shown) is formed on the n-GaN layer 16 and the p-GaN layer 20 so that a current can be applied from the outside.

However, in the nitride semiconductor light emitting device 10, since the sapphire substrate and gallium nitride (GaN) have different lattice constants and crystal lattice, a potential occurs at the interface between the sapphire substrate and gallium nitride (GaN).

To reduce this, a GaN buffer layer was formed on the sapphire substrate to reduce the difference in lattice constant between the sapphire substrate and the GaN layer. However, since the GaN layer was grown at a low temperature, the GaN layer was directly grown on the GaN buffer layer. This causes a large amount of crystalline defects to propagate into the hot growth GaN layer, resulting in a defect called dislocation.

Accordingly, there is a need in the art for a nitride semiconductor light emitting device that prevents defects such as dislocations caused by lattice mismatch between a sapphire substrate and a nitride semiconductor material such as GaN, and has good electrical reliability and characteristics, and a method of manufacturing the same.

It is an object of the present invention to provide a nitride semiconductor light emitting device having excellent light output and reliability of a nitride semiconductor light emitting device and a method of manufacturing the same.

The nitride semiconductor light emitting device according to the present invention,

A first n-GaN layer; A current spreading layer formed on the first n-GaN layer; A second n-GaN layer formed on the current spreading layer; An active layer on the second n-GaN layer; It includes a p-GaN layer formed on the active layer.

In addition, the method for manufacturing a nitride semiconductor light emitting device according to the present invention,

Forming a first n-GaN layer on the substrate; Forming a current spreading layer on the first n-GaN layer; Forming a second n-GaN layer on the current spreading layer; Forming an active layer on the second n-GaN layer; Forming a p-GaN layer on the active layer.

2 is a view showing a laminated structure of a first embodiment of a nitride semiconductor light emitting device according to the present invention.

In the nitride semiconductor light emitting device 100 according to the present invention, as shown in FIG. 2, a buffer layer 104 is formed on a substrate 102. Here, the buffer layer 104 is to reduce the difference between the lattice constant between the substrate and the GaN layer, AlInN structure, InGaN / GaN superlattice structure, In _x Ga _1-x N / GaN stacked structure, Al _x In _y Ga ₁ It may be selected from a stacked structure of _{-x, y} N / In _x Ga _1-x N / GaN.

In the nitride semiconductor light emitting device 100 according to the present invention, after the undoped GaN layer 106 is grown on the buffer layer 104, the first n-GaN layer (on the undoped GaN layer 106 is formed). 108) is formed. The first n-GaN layer 108 is doped with silicon (Si) to lower the driving voltage.

After the first n-GaN layer 108 is formed, the current spreading layer 110a is formed on the first n-GaN layer 108, and after the current spreading layer 110a is formed, the second n-GaN layer ( 112 is formed. The current spreading layer 110a is positioned between the first n-GaN layer 108 or the second n-GaN layer 112 to improve current flow, and includes an indium tin oxide (ITO) material.

Since the current spreading layer 110a has less resistance than the n-GaN layers 108 and 112, the current flows very well, and the resistance of the n-GaN layers 108 and 112 is reduced by about 10%.

Accordingly, when a voltage is applied to the n-GaN layers 108 and 112 in the forward direction, the amount of electrons in the n-GaN layers 108 and 112 may increase.

After the second n-GaN layer 112 is grown on the current spreading layer 110a, the active layer 120 is grown on the second n-GaN layer 112.

Herein, for the growth of the active layer 120, NH ₃ , TMGa, and trimethylindium (TMIn) are supplied using nitrogen as a carrier gas at a growth temperature of 780 ° C., for example, to form an active layer 120 made of InGaN. Grown to a thickness of 120 kPa to 1200 kPa. At this time, the composition of the active layer 120 may be a laminated configuration grown with a difference in the molar ratio of each element component of InGaN.

After the active layer 120 is formed, the p-GaN layer 124 containing the p-type dopant is grown on the active layer 120 to a thickness of several hundred to several thousand micrometers, thereby forming the p-GaN layer 124.

After the p-GaN layer 124 is formed, heat treatment is performed at a temperature of 500 to 900 ° C. to adjust the hole concentration of the p-GaN layer 124 to a maximum, and a barrier layer is formed on the last layer of the active layer 120. (Not shown) may be formed, and a p-type cladding layer (not shown) may be formed between the active layer 120 and the p-GaN layer 124 to increase carrier confinement. It may be.

Meanwhile, an n-type electrode (not shown) may be formed on the first n-GaN layer 108 or the second n-GaN layer 112, through which current is injected from the outside. Alternatively, an n-type electrode may be formed on the current spreading layer 110a.

A method of manufacturing and driving a nitride semiconductor light emitting device 100 according to the present invention having such a structure will be described in detail below with reference to the accompanying drawings.

The buffer layer 104 is formed on the sapphire substrate 102. The buffer layer 104 is composed of a plurality of layers. For example, the sapphire substrate 30 may be disposed in a metal organic chemical vapor deposition (MOCVD) chamber (not shown) or a molecular beam epitaxy (MBE) chamber (not shown). After mounting, silicon is grown on the sapphire substrate 102 by using silane gas (SiH ₄ ) at an ambient temperature of 500 to 600 ° C. to form a silicon layer, and then an InN layer is formed thereon.

The AlN layer is grown on the InN layer by containing Al and N at a predetermined ratio using TMAl (trimethyl aluminum) and ammonia (NH ₃ ), for example, at an ambient temperature of about 1000 ° C.

Therefore, a buffer layer 104 including a silicon layer, an InN layer, and an AlN layer is formed, and for example, NH ₃ and trimetal gallium (TMGa) are supplied onto the buffer layer 104 at a growth temperature of 1500 ° C., An undoped GaN layer 106 containing no dopant is formed to a predetermined thickness.

The first n-GaN layer 108 is formed on the undoped GaN layer 106. The first n-GaN layer 108 is grown to a predetermined thickness by supplying a silane gas including an n-type dopant such as, for example, NH ₃ , trimetal gallium (TMGa), and Si.

After the first n-GaN layer 108 is formed, the first n-GaN layer 108 is formed on the first n-GaN layer 108 by using an indium, tin (Ti) oxide, or a highly conductive material such as Co, W, or Fe. The current spreading layer 110 is grown to a thickness of 100000 mA. The current spreading layer 110 may be grown using organic metal chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), sputtering, electron beam (E-beam) equipment, and the like. This may form a current spreading layer by MBE, sputter, or electron beam while forming the 1n-GaN layer by organometallic chemical vapor deposition equipment.

Here, the current spreading layer 110 may be formed of a metal such as ITO, Co, W, Fe, or the like.

As shown in FIG. 2, the current spreading layer 110 may be grown evenly on the first n-GaN layer 108. As illustrated in FIG. 3, the first n-GaN layer 108 may be formed. It may be grown to have a pattern of a predetermined shape on the). That is, after the current spreading layer 110 is formed on the first n-GaN layer 108 with a thickness of about 4000 kV, the etching apparatus may be formed in a predetermined pattern using etching equipment.

In addition, the current spreading layer 110 may be formed as a flat surface without a constant arrangement thereof, but may be formed in a concave-convex shape. For example, the concave-convex shape may have a rectangular array, or may be grown in a triangular array, a spiral mode, or a lens.

Since the current spreading layer 110 formed as described above is formed at a high temperature of about 1000 ° C. or more, bonding of the ITO layer (indium tin oxide layer) is broken, and indium and tin (Ti) located on the surface of the second n-GaN It is included as an impurity on the layer 112. Indium and tin included in the second n-GaN layer 112 may be located at a defect site to prevent propagation of dislocations of the second n-GaN layer 112 and may cause carrier condensation. Increasing the carrier concentration reduces the operating voltage.

That is, the current spreading layer 110 can effectively spread the current by the n-GaN layer, thereby effectively increasing the uniform operating voltage and the lifetime of the light emitting device, thereby improving reliability.

Subsequently, a second n-GaN layer 112 is grown on the current spreading layer 110, and the second n-GaN layer 112, like the first n-GaN layer 108, is trimetal gallium Silane gas containing n-type dopants such as (TMGa) and Si is supplied and grown to a predetermined thickness.

However, unlike the first n-GaN layer 108, the second n-GaN layer 112 may be grown to have different resistance, carrier mobility, and carrier concentration.

For example, when doping Si to the second n-GaN layer 112, the doping concentration may be adjusted stepwise to form an electron diffusion path by forming a layer inside the GaN layer. In other words, when the Si doping is performed in three steps, in the first step, the Si is doped to have a carrier concentration of 1 × 10 ¹⁹ or more at a high concentration, and in the second step, the doping concentration is linearly reduced. 10 Doped to have carrier closure of ¹⁸ or more.

As described above, multi-step doping prevents local potential generation due to crystal mismatch in the n-GaN layer, thereby reducing the dynamic resistance of electron diffusion in the current-voltage characteristic. The threshold energy for the electron flow on the semiconductor contact surface is reduced resulting in an improved power effect. And the thickness of the second n-GaN layer 112 is 1 ~ 10000Å, it can be grown by controlling the growth rate in multiple stages.

That is, the second n-GaN layer 112 is first grown at a growth temperature in the range of 100 to 800 ° C. at a growth rate of 0.001 to 1 μm / hour, and then at 800 to a growth rate of 1 to 3 μm / hour. Growing at a growth temperature in the range of 1100 ℃ to form the required thickness.

In addition, as shown in FIG. 3, even when the surface shape of the current spreading layer 110b is formed as an uneven shape, the second n-GaN so that the second GaN layer 112 may form a flat surface. Layer 112 is formed to a thickness of at least about 1 μm.

In this case, like the first n-GaN layer 108, the second n-GaN layer 112 formed on the current spreading layer 110b may also include silane including n-type dopants such as trimetal gallium (TMGa) and Si. It is formed by supplying gas, but unlike the first n-GaN layer 108, it is grown so that resistance, carrier mobility, and carrier condensation are different.

The second n-GaN layer 112 has a thickness of 1 to 10000 Pa, and can be grown by controlling its growth rate in multiple stages. For example, the second n-GaN layer 112 is first grown at a growth temperature in the range of 100 to 800 ° C. at a growth rate of 0.001 to 1 μm / hour, and then at a growth rate of 1 to 3 μm / hour. Growing at a growth temperature in the range of 800 ~ 1100 ℃ to form the required thickness.

In addition, the active layer 120 is grown on the second n-GaN layer 112, but for growth of the active layer 120, for example, NH ₃ , using nitrogen as a carrier gas at a growth temperature of 780 ° C. TMGa and trimethylindium (TMIn) are supplied to form an active layer made of InGaN with a thickness of 120 kV to 1200 kV. At this time, the composition of the active layer 120 may be a laminated configuration grown with a difference in the molar ratio of each element component of InGaN.

After the active layer 120 is formed, the p-GaN layer 124 containing the p-type dopant is grown on the active layer 120 to a thickness of several hundred to several thousand micrometers.

After the p-GaN layer 124 is formed on the active layer 120, for example, heat treatment is performed at a temperature of 500 to 900 ° C. to adjust the maximum hole concentration of the p-GaN layer 124.

In the nitride semiconductor light emitting device 100 according to the present invention formed through the above process, the electrode layers are formed through a subsequent process, and when voltage is applied thereto, light is emitted by recombination of electrons and holes in the active layer. That is, as the voltage is applied to the p-n junction in the forward direction, electrons of the n-GaN layer and holes of the p-type GaN layer are injected to the p side and the n side, respectively.

In this case, since the current spreading layers 110a and 110b exist between the first and second n-GaN layers 108 and 112, the current flows better, thereby supplying more carriers to the active layer, thereby improving light emission efficiency. do.

Since the external quantum efficiency is represented by the number of photons emitted per injected charge, it is possible to effectively spread the current by the first and second n-GaN layers 108 and 112 so that the uniform operating voltage and the The lifespan of the light emitting device can be effectively increased, thereby improving reliability.

In addition, in the current spreading layers 110a and 110b and the second n-GaN layer 112 according to the present invention, indium and tin (Ti) are contained on the surface of the second n-GaN layer through the manufacturing process to form the second n- The electrical properties of the nitride semiconductor light emitting device are also improved because it prevents the propagation of potential generated under the GaN layer.

Although the present invention has been described above with reference to the embodiments, these are only examples and are not intended to limit the present invention, and those skilled in the art to which the present invention pertains may have an abnormality within the scope not departing from the essential characteristics of the present invention. It will be appreciated that various modifications and applications are not illustrated.

For example, each component shown in detail in the embodiment of the present invention may be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

According to the nitride semiconductor light emitting device according to the present invention and the manufacturing method thereof, the current flow is improved by forming a current spreading layer between the n-GaN layer, thereby improving the electrical and optical characteristics of the semiconductor device.

In addition, by doping the N-GaN layer in multiple stages, local potential generation due to crystal mismatch in the n-GaN layer is prevented, thereby reducing the dynamic resistance of electron diffusion in the current-voltage characteristic.

Claims (23)

A first n-type semiconductor layer; A current spreading layer on the first n-type semiconductor layer; A second n-type semiconductor layer formed on the current spreading layer; An active layer formed on the second n-type semiconductor layer; It includes a p-type semiconductor layer formed on the active layer, The current spreading layer is a nitride semiconductor light emitting device comprising at least one of ITO (indium tin oxide) and a conductive metal. A first n-type semiconductor layer; A current spreading layer formed on the first n-type semiconductor layer; A second n-type semiconductor layer formed on the current spreading layer; An active layer formed on the 2n semiconductor layer; It includes a p-type semiconductor layer formed on the active layer, The second n-type semiconductor layer is formed by gradually reducing the doping concentration of the n-type dopant, The current spreading layer is a nitride semiconductor light emitting device comprising at least one of ITO (indium tin oxide) and a conductive metal. delete The method according to claim 1 or 2, The conductive metal nitride semiconductor light emitting device comprising at least one of Co, W, Fe. The method according to claim 1 or 2, The current spreading layer is a nitride semiconductor light emitting device, characterized in that formed in a thickness of 1 ~ 100000 Å. The method according to claim 1 or 2, The current spreading layer is a nitride semiconductor light emitting device, characterized in that the surface shape is formed in a flat surface having no arrangement or irregularities. The method according to claim 1 or 2, The current spreading layer is ITO (indium tin oxide), The second n-type semiconductor layer comprises a nitride semiconductor light emitting device comprising indium, tin (Ti) separated from the bonding of the indium tin oxide (ITO) which is the current spreading layer. delete The method according to claim 1 or 2, And the first n-type semiconductor layer and the second n-type semiconductor layer comprise an n-type dopant containing Si. The method according to claim 1 or 2, The second n-type semiconductor layer has a thickness of 1 to 10000Å nitride semiconductor light emitting device. The method of claim 1, And the first n-type semiconductor layer and the second n-type semiconductor layer comprise GaN. The method of claim 9, The second n-type semiconductor layer is nitride semiconductor light emitting device, characterized in that formed in the order of the growth rate of 0.001 ~ 1㎛ / hour and the growth rate of 1 ~ 3㎛ / hour. A first n-GaN layer; A current spreading layer formed on at least one of indium tin oxide (ITO) and a conductive metal on the first n-GaN layer; A second n-GaN layer formed on the current spreading layer; An active layer formed on the second n-GaN; A p-type GaN layer formed on the active layer, The first n-GaN layer and the second n-GaN layer is a nitride semiconductor light emitting device comprising an n-type dopant containing Si. Forming a first n-type semiconductor layer on the substrate; Forming a current spreading layer on the first n-type semiconductor layer; Forming a second n-type semiconductor layer on the current spreading layer; Forming an active layer on the second n-type semiconductor layer; Forming a p-type semiconductor layer on the active layer, And the current spreading layer is formed of at least one of indium tin oxide (ITO) and a conductive metal. The method of claim 14, The current spreading layer is a method of manufacturing a nitride semiconductor light emitting device, characterized in that formed through at least one of organic metal chemical vapor deposition (MOCVD), Molecular Beam Epitaxy (MBE), sputter, electron beam (E-Beam) process . delete The method of claim 14, The conductive metal is a nitride semiconductor light emitting device manufacturing method characterized in that it comprises at least one of Co, W, Fe. The method according to claim 14 or 17, The current spreading layer is a nitride semiconductor light emitting device manufacturing method, characterized in that formed in a thickness of 1 ~ 100000 Å. The method according to claim 14 or 17, And etching the current spreading layer to form a surface shape of the current spreading layer into an uneven shape through an etching process. The method according to claim 14 or 17, The thickness of the second n-type semiconductor layer is 1 to 5000Å, characterized in that the nitride semiconductor light emitting device manufacturing method. The method according to claim 14 or 17, The second n-type semiconductor layer is a nitride semiconductor light emitting device manufacturing method, characterized in that formed by adjusting the doping concentration of the n-type dopant in multiple stages. The method of claim 21, The forming of the second n-type semiconductor layer may include a first step of doping Si to have a carrier concentration of 1 × 10 ¹⁹ or more at a high concentration; A second step of linearly reducing the doping concentration of Si; And a third step of doping the doping concentration of Si to have a carrier condensation of 3 × 10 ¹⁸ or more. The method according to claim 14 or 17, The second n-type semiconductor layer is the first step of growing at a growth temperature in the range of 100 ~ 800 ℃ at a growth rate of 0.001 ~ 1㎛ / hour, And a second step of growing at a growth temperature in the range of 800 to 1100 ° C. at a growth rate of 1 to 3 μm / hour.

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